Abstracts Physics

Production of a cooled ion beam by manipulation of 60-keV ions into a radio-frequency quadrupole ion guide

by Alban. Kellerbauer

An electrostatic deceleration system was developed for the injection of the 60-keV mass-separated ion beam at the ISOLDE facility at CERN (Geneva, Switzerland) into a new segmented radio-frequency quadrupole (RFQ) ion guide at the ISOLTRAP experiment. A detailed computer simulation of the ion motion through the electrostatic decelerating and focusing electrodes into the RFQ ion guide was carried out. A complete decelerating structure was designed and built using the parameters extracted from the simulation, as was the first half of a segmented RFQ ion guide for capturing and cooling the decelerated beam. With experiments conducted partly with the ISOLTRAP apparatus at CERN and partly with our apparatus at McGill University, we were able to show that the decelerating structure can in fact inject a beam into the RFQ ion guide. The measured transmission rate of 15 to 30 percent is in agreement with the value that was predicted by the simulations.